DESCRIPTION (Investigator's Abstract): The applicants plan to study conditions in the developing rodent brain necessary for supporting optic axon outgrowth and for establishing appropriate terminal connections between molecules known to support axonal outgrowth and the extension of retinal ganglion cell axons. In addition, the applicants will examine the conditions that produce optimal outgrowth and formation of connections by retinae transplanted to ectopic sites in neonatal and fetal rodent brains. One series of studies will focus on the outgrowth process itself and the substrates that support it while the other will examine what factors influence the ability of optic axons originating from transplants to innervate visual centers, to compete with other optic inputs for target space and to form topographic maps within visual centers. Such information will provide insight into how the circuitry for optimal visual function is established. It will also define the conditions necessary for creating surrogate pathways to replace damaged primary optic connections.